Miscellaneous oil refers to the oil that accidentally enters the metalworking fluid, which is the main reason for the failure of the metalworking fluid. They change the chemical composition of the working fluid and affect the accurate concentration measurement of the metalworking fluid.
There are several sources of miscellaneous oil entering metalworking fluid:
1. Machine tool lubricating oil. Including hydraulic oil, guide rail oil, spindle oil and Gear Oil. 2. Enter from the surrounding environment. When the floor or machine tool is cleaned, oil leaks or is flushed into the metalworking fluid system. 3. Cutting oil is used in the last processing procedure, or parts are coated with antirust oil (this is the most troublesome thing), and parts are brought into the metalworking fluid system.
The professionals of metalworking fluid classify the machine tool oil into three states:
1. Miscellaneous oil in free state. When the metalworking fluid is stationary or the centralized circulating cooling system is shut down, it floats on the surface of the metalworking fluid. 2. Miscellaneous oil in dispersed state. Mechanically dispersed into the metalworking fluid (if the metalworking fluid is stationary enough, the oil will float to the surface). 3. Emulsified miscellaneous oil. These oils enter the metalworking fluid system in an emulsified manner and remain stable for a long time.
Main influence of machine tool impurities: 1. Surface residues on machine tool parts and working environment; 2. Smoke and oil mist are generated in the workshop environment; 3. Obstruct the filtering work of the filtering system; 4. Stimulating the reproduction of bacteria and producing odor; 5. The wettability of metalworking fluid products is reduced, and the workpiece and iron filings are rusted; 6. Reduce the ability of Metal Working Fluid to take away heat; 7. Some miscellaneous oils contain surfactant, which makes metalworking fluid produce foam; 8. If the oil contains active sulfur or zinc thiophosphate, it may cause dermatitis; 9. It is difficult to control and measure the concentration of metalworking fluid; 10. Cause loss of wetting agent, reduce surface finish of metal parts and tool life. On the machine tools with more impurities, the negative effects of the impurities are obvious. In the centralized cooling system, the negative effect of miscellaneous oil is greater. Due to the small amount taken away, the miscellaneous oil is easy to accumulate. Due to the continuous circulation of the system, the pump mixes the miscellaneous oil into the metalworking fluid system to disperse or emulsify it. Generally speaking, when the impurities of the machine tool are less than 2%, there are few problems; When it is higher than 2%, we begin to see bacteria begin to multiply in large quantities; When it is higher than 4%, tool life, part finish, oil mist and surface residue become problems. The influence of miscellaneous oil from different sources is also different. Even if the wax containing rust inhibitor is only 0.5%, it can cause serious problems. The contamination of machine tool oil shall be minimized and removed from the system as soon as possible.
